In an imaging system for percutaneous transluminal coronary angioplasty (PTCA) in catheter laboratories, for example for treatment of cardiac stenoses, a catheter is inserted into the vascular system at an access site. During the intervention, a flexible, partially or fully radio-opaque guidewire is advanced to the affected vascular structures (e.g. stenoses in coronaries, neurovascular aneurisms, or arteria-venous malformations). Fluoroscopic low-dose x-ray surveillance visualizes the guidewire and allows for the hand-eye-coordination of the interventionalist while advancing the guidewire. When positioned, the guidewire serves as rail to deliver interventional devices (e.g. balloons for dilation and stent delivery, detachable coils for aneurysm clotting). The delivery and deployment of the interventional devices is also fluoroscopy-controlled. US 2009/0208078 describes automatically associating coronary arteries with regions of the myocardium to which the arteries supply blood. The method uses three dimensional image data of a patient, and an axial image slice is used to identify candidate locations of the aorta.